There really is no standard or goal, it is as much science as it is luck.  There is the silicon lottery, which is why when all other hardware is the same 2 different CPUs of the same line will perform similar and overclock completely differently.
 
Overclocking is at its most base level simply pushing the hardware to run above spec speeds. 
 
What is your full system specs, what do you use your PC for, and what is the goal of this overclock?

I'm what you might call a "casual" or "rookie" overclocker.   I do it just to see if I can do it and how many more points it could or would add to a benchmark.  But at the end, I either leave things at stock or simply use the motherboards built in OC utilities.
 
It's much easier to do these days than it was 10 years ago.  
 

look it up on youtube, that's how I learnt